Bone Structure and Function PDF

Bone Julie Watson GDC learning outcomes 1.1.5 1.1.6 1.17 2  Loading… Bones work with muscles and joints to hold our body together and support freedom of movement. This is called the musculoskeletal system. Learning Outcomes By the end of this...

Bone Julie Watson GDC learning outcomes 1.1.5 1.1.6 1.17 2  Loading… Bones work with muscles and joints to hold our body together and support freedom of movement. This is called the musculoskeletal system. Learning Outcomes By the end of this session students should be able to: Describe the composition and development of bone Identify the different types of bones and where they are found Be aware of the general function of the bone types in the body. Describe the process of bone healing and the factors that influence healing Recognise some common bone diseases patients may present with. *There is an expectation that this subject is a revision of prior human biology learning 4 Why learn about bone? Loading… 5 Pngimg.com Types of Bone 6 The five different types of bones in the body Long bones Consist of a long shaft or diaphysis and two articular surfaces , with central bone marrow cavity E.g. limb bones such as tibia or femur Short bones Cube shaped bones E.g. wrist and ankle bones Flat bones Thin and often curved E.g. skull bones such as occipital bone or parietal bone Irregular bones Irregular and complicated shapes E.g. bones of spine Loading… Sesamoid bones Embedded in tendons E.g. the patella Functions of Bone 12  Development of Bone Begins before birth and is complete at approximately 25 years of age 2 main types: Intramembranous ossification Endochondral ossification https://www.britannica.com/science/bone-formation https://www.nature.com/articles/s41580-020-00279-w https://www.intechopen.com/chapters/64747 https://www.ncbi.nlm.nih.gov/books/NBK539718/ Bone Structure: Cells present Osteoblasts Bone forming cells Single nucleus Immature bone cells Become trapped and isolated in lacunae as bone develops  Osteocytes Originate from osteoblasts that have become trapped in lacunae Mature bone cells Many processes  Osteoclasts Bone resorption cells Large and multi-nucleated Can engulf like macrophages Maintain the optimum shape of bone Activity takes place at the bone surface A fine balance of osteoblast and osteoclast activity maintains normal bone  Bone is one of the hardest tissues in Composition of the body when fully developed Bone (dental enamel is the hardest) Fully developed bone consists of: 40-50% 20% An organic compound - any Inorganic Water 30-40% Organic member of a large class of chemical compounds whose molecules contain carbon Inorganic material - inorganic compounds are considered to be of a mineral, not biological,  origin Bone is made up of osteocyte cells, collagen fibres and an intracellular matrix containing inorganic salts such as calcium and phosphate It is strong and rigid, suited to supporting and protecting some of the more delicate body structures It is a vascular tissue with a large capacity for growth in the first two decades of life and regeneration throughout life  Bone Structure: Matrix INORGANIC: Crystalline mineral salts & calcium Hydroxyapatite crystals Initial matrix is non mineralised osteoid Alkaline phosphatase promotes crystal growth centres ORGANIC: Mainly collagen  Bone Structure The structural and functional unit of bone is the osteon or Haversian system Each Haversian system or osteon has a central Haversian canal which runs longitudinally throughout the system, carrying blood vessels, lymph and nerves Types of Bone Tissue 22  Compact bone Appears solid macroscopically Contains large numbers of Haversian systems microscopically Cancellous or spongy bone: Appears spongy macroscopically Contains red bone marrow The Structure of Compact Bone The strongest form of bone tissue Very few spaces Forms tough outer layer of each bone, and adds support and protection to the skeletal system Approximately 80% of our skeleton is compact bone  The structure of compact bone Surrounding the canal are concentric rings of flat bone known as lamellae which make up osteons The structure of compact bone Between the lamellae are spaces known as lacunae which contain lymph and osteocytes Canaliculi link the lacunae with the lymph vessels allowing osteocytes to obtain nourishment The Structure of Cancellous or Spongy Bone Much lighter type of bone Branching bars and plates of bone tissue Makes up the inside of short, flat and irregular bones and the epiphyses of long bones Does not contain osteons Lamellae arranged in irregular lattice of thin columns or trabecular, surrounding red bone marrow  Bone Structure: Periosteum The surface of bone is surrounded by this vascular fibrous membrane Functions: Provides nourishment by facilitating the passage of blood vessels to the bone Gives attachment to muscle tendons Assists in bone formation and repair Stages of Bone Healing Loading… https://www.youtube.com/watch?v=N391iuWbM0s https://www.youtube.com/watch?v=ktWiW6yssbU Stages of Bone Healing Formation of a fibro cartilaginous primary callus during the first months after injury The dead bone is resorbed, and spongy bone appears The size of the callus is affected by the immobility of the fracture site; the smaller the amount of movement, the smaller the callus  Stages of Bone Healing Spongy bone is gradually replaced by lamellar bone The fracture is united by this bony secondary callus  Stages of Bone Healing The final phase is remodeling The shape of the bone is gradually returned to normal This may take several years Factors that can delay healing Infection Tissue fragments between the ends of bone Deficient blood supply - delays in bone formation of granulation tissue Old age - healing becomes slower Medications e.g., steroids The host response Factors that can improve healing Limited movement/resting of the broken bone Medication ? Pain relief, you don’t heal when in pain! Nutrition Appropriate movement under guidance Age (younger the better)  Acromegaly – overgrowth of bones Bone Conditions in the face, hands and feet Fibrous dysplasia – abnormal growth or swelling of bone Rickets – a child’s growing bones fail Some conditions of bone to develop due to a lack of vitamin D include: Multiple myeloma – cancer of the plasma cells in bone marrow Fractures – broken bones of various *Bone cancer – primary bone types cancers include osteosarcomas and chondrosarcomas. However, most Osteoporosis – loss of bone density cancers found in bone have spread and strength from other organs such as the *Osteomyelitis – infection of the breast, prostate, lung or kidney. bone Osteitis – bone inflammation, for example, Paget’s disease of the bone Osteomyelitis - Infection of bones, a serious condition common in long bones of the arms and legs but can be present in the mouth. Microbes such as Staphylococcus Aurous gain access to bone and spread infection which may become chronic. This happens when the bone is exposed and becomes infected.  Bone tumours are commonly linked to other pathology Cancerous pathology of bones are frequently metastases(transfer of malignant cell from one part of the body to another) of primary carcinomas of breast, lungs and prostate gland. Look carefully at the radiolucent area, shown by the arrows Recommended reading for Bone and Cartilage https://cartilage.org/patient/about-cartilage/what-is-cartilage/ https://www.histology.leeds.ac.uk/bone/cartilage.php https://www.histology.leeds.ac.uk/bone/bone.php Ross and Wilson Anatomy and Physiology text book Cartilage and Bone chapters 38